1. Field of the Invention
This invention relates to Optical Network Nodes (ONNs), and, in particular, to a method, apparatus, and program for verifying the operation and configuration of an ONN that includes at least one optical broad-band amplifier and a channel selective filter, using a lasing effect.
2. Description of Related Art
Modem Dense Wavelength Division Multiplexing (DWDM) optical networks, such as the Tellabs® 7100 Optical Transport System, include a significant number of optical channels. In such networks, optical fiber connections in every node must be verified to confirm that they are operational for every channel. Each network node typically also needs to be pre-configured, or “base-lined”, for every channel prior to interconnecting any transponders.
It is becoming a more common practice to use broad-band Amplifier Spontaneous Emission (ASE) noise produced by optical amplifiers, that are a part of every node, in node configuration verification procedures and conducting base-line measurements. Such procedures typically are used in open loop systems.
However, optical network nodes typically include channel selective filters, such as ROADM, Wavelength Blocker, or DGEF modules that introduce access to every channel, and unfortunately, these filters typically can introduce significant optical losses. In addition, use of a large number of channels leaves only a very small fraction of the optical energy contained in the ASE noise in each channel bandwidth.
Because of the high optical losses in the filters and the large number of channels through which ASE noise energy must be divided, it often is necessary to generate very high ASE noise power (e.g., 20 dBm or greater) in the above prior art nodes, or to increase the complexity of per-channel optical power detectors, or both. Either case can be expensive and requires use of complex optical components such as power detectors, transponders and the like, despite the fact that the components might be used only once. There is a need, therefore, to provide an improved technique for performing node configuration verification procedures, that overcomes the foregoing deficiencies.